This invention relates to new lubricating agents for processing yarns, or lubricating finishes of yarns and methods of processing thermoplastic synthetic yarns by using such lubricating agents, and more particularly to novel lubricating agents of a type never proposed before, having as their principal constituent polyalkylene ether carbonate to provide excellent lubricity and antistatic properties and to demonstrate much superior property regarding the rate of generating tar and strength in oil membranes as compared to conventional lubricating agents and methods of processing thermoplastic synthetic yarns by using such lubricating agents.
Various kinds of thermoplastic synthetic fibers such as polyester, polyamide, polypropylene, and polyacrylonitrile and cellulose-type yarns such as acetates are made into a cloth through processes such as weaving, drawing, false twisting, twisting and sizing as well as spinning and knitting; some of these processes may be combined into one process under certain circumstances. Various kinds of lubricating agents are used in these processes.
It has been well known that these lubricating agents must have lubricity and antistatic effects and be able to reduce the rate of generating tar. For this reason, use has long been made not only of mineral oils and aliphatic esters but also of polyoxyalkylene ethers (for example, U.S. Pat. No. 3,338,830). Of the lubricating agents which make use of these compounds, polyoxyalkylene ethers have the best properties regarding the rate of generating tar but they, too, cannot be sufficiently satisfactory under the severe conditions of thermal processing (such as draw-false twist-texturing with yarn speed in excess of 600 m/min).
It is therefore desirable to provide a lubricating agent with a better characteristic regarding the rate of generating tar than conventionally used polyoxyalkylene ethers. Nowadays, attempts are being made to increase the processing speed in order to improve the production efficiency while deniers of filament yarn are becoming finer for the fabrication of products of higher and more discriminating qualities. This tends to cause the sliding yarn to break more easily, more fuzz to appear and electrostatic problems to occur more frequently. In the case of high-speed draw-false twist texturing (with the yarn speed in excess of 600 m/min) of spin-draw process at high temperatures (over 200.degree. C.), there is a strong demand for improvements regarding tar depositing on heaters and friction on metallic materials with which the sliding yarn comes into contact. Accordingly, it is not a matter of mere desire to make improvements on already available lubricating agents. There is a serious demand for new lubricating agents which, while maintaining the lubricity and antistatic properties of the conventional lubricating agents, stringently satisfy the requirements of significantly reducing the rate of generating tar and providing strong oil membranes.